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W 2800.7 F532r/w no.32
F-50-R-17 2010 c.1
FINAL REPORT
FEDERAL AID GRANT NO. F-50-R-17
Fish Research for Oklahoma Waters
PROJECT NO. 32
Growout channel catfish stocking evaluation of Oklahoma's small
impoundments
OKLAHOMA DEPARTMENT OF WILDLIFE CONSERVATION
JANUARY 1, 2010 through DECEMBER 31, 2010
FINAL REPORT
State: Oklahoma Grant Number: F-50-R-17
Grant Title: Fish Research for Oklahoma Waters
Project Number: 32
Project Title: Growout channel catfish stocking evaluation of Oklahoma's small
impoundments
Project Leader: Greg Summers
Contract Period: From: January l, 2010 to: December 3l, 2010
I. Project Objective: Determine/calculate 1.) catch rates, length frequencies, condition, and
age structure on nine small lakes before and after experimental stocking rate
manipulations and 2.)angler catch rates and satisfaction before and after stocking rate
manipulations on nine small lakes.
II. Summary of Progress
A. Introduction
Channel catfish (lctalurus punctatus) are stocked in small impoundments throughout
Oklahoma as put-grow-take or put-take fisheries. These stockings are necessary to
sustain an acceptable sport fishery as natural recruitment of channel catfish in small
impoundments is often low (Santucci et. al. 1994). It is important these stockings make a
significant contribution to the fishery as the Oklahoma Department of Wildlife
Conservation (ODWC) invests considerable resources in them.
Channel catfish are difficult to sample in small impoundments with most gear types. As
a consequence, the ODWC has conducted few catfish surveys on small lakes. Recently,
tandem hoop nets (3 tied in a series) have been used to effectively collect these fish in
small impoundments (Flamming and Schultz 2007, Michaletz and Sullivan 2002).
Tandem hoop nets collect channel catfish more efficiently than gill nets or electrofishing
and also produce representative samples offish >250 mm (Buckmeier and Schlechte
2009, Michaletz and Sullivan 2002).
Many small impoundments are stocked annually with growout (229 mm) channel catfish
at rates as high as 99 fish/ha. It is possible that some of these small bodies of water are
overstocked as stocking rates remain high and the number of catfish anglers in Oklahoma
have decreased since 1996 (US. Dept. ofInterior et. al. 2006). Michaletz (2009) found
size structure, condition, and growth to be highly variable on 60 small impoundments in
Missouri; therefore he suggested that stocking rates be individually determined for each
lake.
The population structure of channel catfish in department lakes needs to be determined as
well as stocking rates evaluated. Since channel catfish are one of the few species
managed in small impoundments by stocking, the number of fish stocked can have a
direct effect on angler catch rates and satisfaction. Reduced stocking rates could
potentially improve the size structure of overcrowded populations and in turn increase
angler satisfaction. Unless angler catch rates and satisfaction are negatively impacted,
reduced stocking rates could also potentially free hatchery ponds and resources for
production of other species.
B. Methods
Population characteristics
Nine small impoundments, American Horse, Burtschi, Dahlgren, Evan Chambers, Hall,
Nanih Waiya, Ozzie Cobb, Raymond Gary, and Watonga, were sampled with tandem
hoop nets (three in a series) during July and August 2009. Historically these lakes have
been stocked annually in August through October with growout (229 mm) channel catfish
at the rate of 99 fishlha. These impoundments are highly diverse, ranging geographically
from the panhandle in Northwest Oklahoma to Southeast Oklahoma. The nine lakes
range in size from 14 to 96 ha and encompass trophic levels from oligotrophic to
hypereutrophic. In addition to channel catfish, these impoundments primarily support
populations of sunfish, largemouth bass, and crappie.
Each tandem hoop net set consisted of three hoop nets that were approximately 3.4 m
long with seven fiberglass hoops. The largest hoop was .8 m in diameter at the mouth
and successive hoops slightly decreased in size to the cod end. Two hoop nets with 25-
mm-bar mesh and one hoop net with 12.5-mm-bar mesh were randomly ordered in each
series. Hoop nets were connected mouth to cod end by bridles that were l.8 m total
length. This allowed nets in a series to be fished approximately 0.9 m apart. Each net
was baited with approximately 0.9 kg of cheese log in a 907 g plastic sample jar with
approximately 25 to 30 holes that were 6 mm in diameter.
Effort at each lake was determined by lake size: <20 ha -3 series, ::::2:0 and <61 ha - 5
series, :::::61to <1Olha - 8 series, :::::1 01ha - 10 series (Kline et al. 1995). Sites were
randomly selected in the littoral zone at each lake. Nets were set parallel to the shoreline
in 2.4 to 3.7 m of water to limit by-catch of turtles. If insufficient depth or anoxic
conditions were encountered « 4mg/ml in 8 to 12 feet of water), nets were set
shallower. Shorelines with more than a 45° slope were avoided to keep hoop nets from
rolling to deeper water. Tandem hoop nets were fished for 72 h before being retrieved.
All channel catfish collected were measured (mm.TL), and 20 fish from each 20 mm
length group were weighed and retained for age determination by lapilli (Long and
Stewart 2010) otoliths. All other fish were released back into the lakes. Catches were
recorded separately by each net but were pooled by series to express CPUE as number
of channel catfish per series.
CPUE and mean length were calculated at each lake and compared among lakes. Size
structure at each lake was analyzed by length frequency histograms and PSDs. In
addition relative weights (Wr) were determined for the overall population as well as
specific length groups. Mean length at age was determined from age analysis oflapilli
otoliths using methods described by Mauck and Boxrucker (2005). Since some lakes
were stocked with fish from one cohort in different years, Von Bertalanffy growth
curves were used to estimate length at age in the respective year. Total annual
mortality was determined from catch curve data.
Angler survey
In order to assess channel catfish angler catch rates and satisfaction, a survey box was
placed in a high traffic area at each lake at the beginning of October 2010. A sign was
attached above each survey box to encourage catfish anglers to complete a survey
(Figure 1). Survey cards briefly explained the purpose of the survey and asked party
size, hours spent fishing, number of channel catfish caught and kept, length of fish
caught and kept, and satisfaction of number and length of fish caught (Figure 2).
Anglers were given the choice to either drop the completed survey in the box or mail it
in with prepaid postage.
The total number of anglers, hours of angling effort, and number of fish
caught/kept were summarized for each lake. The number of angling hours required per
fish, mean length of fish caught/kept, percentage of fish caught that was kept, and mean
satisfaction for number and length of fish were also calculated for each lake.
C. Results/Discussion
Population characteristics
Overall, the nine lakes sampled yielded a mean catch rate of 80 fish/series with 3,922
channel catfish being caught from the nine lakes in 2010. Catch rates varied substantially
among lakes. Raymond Gary and Ozzie Cobb produced the lowest CPUE (5 fish/series,
n=54 and 18 fish/series, n=90, respectively) while Burtschi and Watonga had the highest
CPUE (172 fish/series, n=I,372, and 135 fish/series, n=676, respectively). The other
lakes yielded catch rates between 51 and 103 fish/series (Table 1). Mean length among
lakes ranged from 374 mm at American Horse to 293 mm at Burtschi (Table 1).
Growth seemed to be negatively correlated with relative abundance suggesting density
dependence. Results from length at age data suggest channel catfish from American
Horse and Raymond Gary had the highest mean length at age while channel catfish from
Evan Chambers and Burtschi grew slowest (Table 2). Fish stocked in Dahlgren, Nanih
Waiya, and Ozzie Cobb, reached 305 mm within one year after being stocked. Lakes
American Horse and Raymond Gary were similar in length after the first year of growth
at 301 and 299 mm respectively. Channel catfish at lakes Burtschi, Hall, and Watonga
did not reach 305 mm until the third year after being stocked, while it took fish at Evan
Chambers five years to reach this size. Catch curve analysis from length at age data
indicated mortality was moderately high and similar among lakes (44%-59%) except at
Chambers where it was 34% (Table 1).
Length frequencies and low PSDs further indicated a proportionally large number of
small individuals in lakes Burtschi, Chambers, Hall, and Watonga (Figure 3, Table2). In
addition, Dahlgren and Nanih Waiya also had a low proportion of quality size individual
as indicated by PSDs (Table 4). Low PSDs are often an indication of slow growth (Guy
and Brown 2007). Channel catfish populations at American Horse, Ozzie Cobb and
Raymond Gary had higher PSDs and resembled more of a balanced population.
Relative weights ranged from 93 at Burtschi to 79 at Raymond Gary (Table 3). Body
condition did not seem to be associated with growth as Raymond Gary, Ozzie Cobb,
Dahlgren, and Nanih Waiya. All had substantially lower relative weights than the other
populations. At the time of sampling, these four lakes were all stratified at <3 m with no
dissolved oxygen in the hypolimnium while the other lakes supported dissolved oxygen
at depths >5 m. Thermal stress and reduced dissolved oxygen may have exacerbated the
poor body condition of channel catfish in these lakes.
Angler survey
Twenty-nine angler surveys were received between October and December 2009. Lake
Burtschi had the highest number of respondents (n=8) while no surveys were received
from Lake Ozzie Cobb. The mean catch rate (no./hour) channel catfish was lowest at
Watonga (0.014). The other lakes were substantially higher ranging from (0.125 at Nanih
Waiya to (0.667) at Raymond Gary and Burtschi. Mean length offish caught by anglers
at each lake was similar to mean length obtained from tandem hoop net samples. Anglers
from American Horse, Nanih Waiya, and Raymond Gary kept an average of>67% of the
fish they caught while all other lakes kept <20% of fish caught. Satisfaction for number
offish caught and length offish was highest at Lake Nanih Waiya and lowest at Lake
Watonga.
D. Conclusions/Recommendations
• Relative abundance, as measured by tandem hoop nets, was highly variable
among lakes. Growth seemed to be negatively correlated with relative abundance
suggesting density dependence.
• Length frequencies and low PSDs further indicated slow growth at Lakes
Burtschi, Evan Chambers, Hall, and Watonga.
• Relative weights (Wr) were not associated with growth. Environmental
conditions such as temperature and dissolved oxygen may be related to body
condition.
• The angler survey should continue through September 2011. If angler survey
returns continue to be low, interviews will be conducted to increase the number of
respondents.
• All nine lakes should be sampled in 2011 to determine catch rates, length
frequencies and body condition.
• Lakes with slow growth and high relative abundance (Burts chi, Evan Chambers,
Hall, and Watonga) should be stocked with 13 fish/ha while lakes with fast
growth rates and moderate abundance (American Horse, Dahlgren, and Nanih
Waiya) should continue to be stocked with 99 fishlha. Stocking rates at Raymond
Gary and Ozzie Cobb should be increased to 150 fish/ha as they exhibited fast
growth but had low relative abundance.
III. Significant Deviations: None
Preparedby: _
Chas Patterson, Senior Fisheries Biologist
Date:
Approved by:_---'-"0IY